The proposed project will study the determinants of occupational fertility differentials in an historical and comparative context, centering on an explanation of the observed high fertility of coal mining populations in Western Europe and North America. In order to obtain more homogeneous populations, data will be collected for the smallest geographical units available in published or archival form. Whenever vital and census data are cross-classified by occupation, these will be used. A further attempt to probe more deeply into the nature of these populations will be a study of local records in a small region of an industrial area of Germany in the 19th and early 20th centuries. The central theoretical focus will be an attempt to relate this empirical work to the body of literature dealing with the economic theory of fertility. It is hoped that a basic understanding of the influence of the choice or fact of occupation on decisions to marry, form households, and bear children can be achieved. The existence of consistently high (relative) fertility among coal mining populations gives promise that this occupational group, which has been relatively large in a number of industrialized nations in the past and which also tends to be geographically concentrated, might furnish clues as to the role of economic factors in fertility behavior and in the fertility decline in the presently developed nations.